In the present work, we analyze acousto-optic (AO) interactions between
acoustic waves (AW) and circularly polarized optical eigenwaves in
gyrotropic crystals. We find that the AO diffraction of circularly
polarized eigenwaves can be divided into six different interaction
types. Contrary to the AO interactions analyzed earlier for the case
of linearly polarized optical eigenwaves, we distinguish three
isotropic interaction types and three anisotropic ones. Moreover,
unlike the isotropic AO interactions of linearly polarized eigenwaves
of
n
o
-
n
o
and
n
e
-
n
e
interaction types, the effective
elasto-optic coefficient (EEC) in the case of interactions between
circularly polarized eigenwaves does not depend on the sign of an
incident circular optical wave. The anisotropy of the EEC and AO
figure of merit is analyzed for a particular case of lead germanate
crystals,
P
b
5
G
e
3
O
11
. We demonstrate that the maximal AO
figures of merit are achieved for type I isotropic diffraction at the
quasi-longitudinal AW. Our calculations are confirmed by the
experimental data obtained for the EEC using the Dixon–Cohen method.
The experiment is concerned with the AO interactions of circular
eigenwaves in
P
b
5
G
e
3
O
11
.